Heterocyclic thiol-based sulfenimide compounds

Abstract

Heterocyclic thiol sulfenimide compounds are useful as an accelerator in the curing of natural and/or synthetic rubbers. The compound can be represented by the formula <IMAGE> wherein each of A1 and A2, independently, is at least one heterocyclic ring containing one or more nitrogen atoms therein, or at least one heterocyclic ring containing one or more nitrogen atoms therein and (1) one or more hydrocarbyl substituents, or (2) one or more electron withdrawing groups, or (3) one or more electron releasing groups, wherein A1 alternatively is thiazyl or a dithiocarbamoyl, and wherein R is a (a) hydrogen atom, or (b) a hydrocarbyl radical having from 1 to 16 carbon atoms, or (c) the hydrocarbon radical of (b) wherein one or more of the carbon atoms is an oxygen atom, a nitrogen atom, or a substituted nitrogen atom wherein said substituted group is an alkyl and in combination with said nitrogen atom forms a heterocyclic ring having a total of from 1 to 7 carbon atoms, or (d) the hydrocarbyl radical of (b) containing a halogen, an amino, a cyano, an alkoxy, a hydroxy, or an alkoxycarbonyl. When the heterocyclic thiol sulfenimide compound is utilized as an accelerator for rubber, improved cure rates, longer scorch delay, and better reversion resistance are obtained in comparison to conventional sulfenamides.

What is claimed is: 
     
       1. A heterocyclic thiol-based sulfenimide compound having the formula ##STR4## wherein each of A 1  and A 2 , independently, is pyridyl, and wherein R is a (a) hydrogen atom, or (b) a hydrocarbyl radical having from 1 to 16 carbon atoms, or (c) the hydrocarbon radical of (b) wherein one or more of the carbon atoms is an oxygen atom, a nitrogen atom, or a substituted nitrogen atom wherein said substituted group is an alkyl and in combination with said nitrogen atom forms a heterocyclic ring having a total of from 1 to 7 carbon atoms, or (d) the hydrocarbyl radical of (b) containing a halogen, an amino, a cyano, an alkoxy, a hydroxy, or an alkoxycarbonyl. 
     
     
       2. A compound according to claim 1, wherein R is an alkyl containing from 1 to 8 carbon atoms. 
     
     
       3. A compound according to claim 1 which is N,N-bis(2-tyridyl)-t-butyl sulfenimide, N,N-bis(2-pyridyl)-isopropyl sulfenimide, or N,N-bis(2-pyridyl)-cyclohexyl sulfenimide.